Adjustable rack and pinion gearing



Oct. 11, 1949. J. H. WORTHEN ADJUSTABLE RACK AND PININ GEARING III FiledOct. 17. 1944 mvEN-ron gfo/f' H War/a E Mw ATTORN EYS a hand for movingover a dial.

Patented Oct. 1l, 1949 vA DJUS'IBLE RACK AND PINION GEARINGl John H.Worthen, Providence, R. I., assignorto Federal Products Corporation, acorporation of- Rhode Island Application October 17, 1944, Serial No.559,072 'I This invention relates to a dial indicator.

A dial indicator of the type referred to consists oi a casing and a geartrain mechanism within that casing forV multiplying and conveyingmovement oi a contact plunger or iinger to The casing usually provides afront wall which has mounted therein a bearing for the staff upon whichthe indicatingv hand is mounted. This bearing is usually carried by thisfront plate oi the casing and remains with this frontplate at all times.Thus, when the gear train mechanism is withn drawn the staff is drawnout of this bearing.

Little or no trouble is experienced in this type` of mounting when thegears in the gear train are all complete circular gears. However, whensegmental gears are used the looseness of the staff when Withdrawn fromthe bearing of the front plate frequently permits many of the gears ofthe gear train to come out of mesh and considerable difficulty isexperienced in the positioning of the gear train mechanism in a casingso that it will properly operate.

One of the objects of this invention is to provide an arrangement sothat the gears of the operating mechanism will not become disengagedthrough handling and prior to or during the as-' sembly of the mechanismin its case.

Another object of this mechanism is to provide a unit which will besubstantially complete and will not depend upon any bearing in thecasing for the mounting of any part of the mechanism.

Another object of this mechanism is to provide an arrangement completelyindependent of the dial hand staff for centralizing the gear trainmechanism in the casing.

Another object of this invention is to provide an arrangement so that amovement may be had of the gear train mechanism and the operating rackof the casing so that a convenient assembly of the two with the propermeshing of the pinion and rack may be had.

With these and other objects in View, the invention consists of certainnovel features of construction, as will be more fully described andparticularly pointed out in the appended claim.

In the accompanying drawings:

Fig. 1 is a top plan View of a dial indicator of the type which is thesubject of this invention;

Fig. 2 is a section approximately on line 2 2 1 Claim. (Cl. i4-422) oi-Fig. 1 butA showing some of the operating parts in full instead of insection;

Fig. 3 is a fragmentaldetail of one part of the casing;

Fig. 4 is an edge View of the separable unit which is placed in thecasing; v Fig. 5 is a plan view of the casing prior to the assembly ofthe unit therein;

Fig. 6 is a plan viewof the vvunit for assembly in the casing in Fig. 5;

Fig. 7 is a view similar to-Fig. 5 but showing the unit of Fig. 6assembled in the casing with the gearing beneath the-plate of the unitdotted to show the relative position thereof. In proceeding with thisinvention, I provide a pair oi plates held in spaced relation formount-V ing the complete gear train and dial hand stall for thetransmission of motion to the dial indicator. One of these plates is soshaped as to fit snugly with the casing in which it is to be assembledso as to centralize and hold the movement in position therein. The staifor the dial hand has its bearings in the plates and extends through anopening in the front plate of the casing out of contact with the wallsthereof.

With reference to the drawings I designates generally a casing whichconsists of a cylindrical side wall II and a front wall I2 having anopening I5 therein. A stem I3 having a bore I4 extends from the sidewalls as shown in Figs. 2 and 5. A back Wall or cover I6 ts into arecess I'I in the side wall II and is secured in place by screws I8engaging the threaded openings I9 in the bosses 2D formed integral withthe side wall A plunger 2| is slidably mounted in the bore I4 of thestem I3 and is provided with a rack 22 formed therein. A pin 23 extendsfrom this rack and the plunger is moved outwardly from the casing by aspring 24 which engages the pin 23 and is anchored to one of the bosses20 or to the securing screw which extends therethrough.

A complete unit designated 25 contains the operating mechanism for theindicator and m'ay be positioned into the casing or taken bodilytherefrom. This unit consists of a front plate 26 and a back plate 21.These plates are spaced apart by a plurality of posts 28 held by screws29 in xed relation to the plates 26 and 2l, which provides a frameworkin which the movable parts of the indicator are mounted. A stai 30 isrotatably mounted in both plates in bearings 3| and 32 provided in theseplates. These bearings have a press ilt with each of the plates andremain as a permanent part of the unit assembly. A gear or pinion 33 ismounted on this staif 30. A segmental gear 313 is mounted on shaft 35having bearings in the plates and engages the pinion 33. Upon this shaft35 there is also mounted a pinion 36 so as to rotate with the shaft 35.Another segmental gear 3l mounted on shaft 38 having bearings in theplates meshes with pinion 3G while a pinion 39. is mounted on shaft 38so as to rotate therewith. The pinion 39' is -for en.- gagement with therack 22 on the plunger 2|.

Another segmental gear 40 is mounted on fai gear and the pinion inone.directionL thefary rangement being such as to bring the pointer backto zero as well as assisting in. returning A suitable springiW-factsupon-this the gear mechanism to zero 'and "causing the' plunger to moveout of the casing.

The entire unit 25 ist-positioned in the casing .l-'L sothat the sta' 3Uextends throughpthe opening I5 in the front/wall. |2 thereof. The points115.45475, 1.8,l ofthe plate 27|, engage.1 rthe inner surface Yofthecylindrical wall ofythe asingsoasto Alocate the. unit -ina position `sothat the staff V3|) passes:1 through the opening lwithoutoontact with.Athe edges thereof. In positioning this unit inithe fcasing., pinion;38,- will be rst. located somewhat -r to:- the left of; the' rack 22andthen'by'turning thefunit such asshown irl-Fig 6. or; ffcounter-clockwise. the pinion/33 will be brought intgokengagementWithvthe, rack so thatthe. teeth: of the twowill-,properly mesh. Anydesired entrance-of the-teethone- With-the othermayf be, lobtainedby'the rotationI of the unit 25m-.the casing.. WhenY this desired-:amounthasbeenfobtainedfthe casing; will' .bef looked in position by.pressure-of thefcover againstz'the-'unit l forcing the front Wall 26thereof snugly against the front Wall l2 of the casing.

After this assembly has been had a suitable dial 5U will be positionedon the front Wall l2 of the casing. A dial hand 5| will be provided onthe staff 30 and a glass cover or lens 52 mounted in bezel '53 may bepositioned over the dial and hand so as to protect the same.

The projection54 on the rear wall IS will serve for mounting the dial insuitable location.

It will be readily apparent that with the unit 25 assembled prior topositioning in the casing none of the gears may becomedislodged or outof. mesh bfyfreason of suchpositi'oning. Also by reason of the unitbeing rotatable to position Athe pinion into the rack a proper mesh maybe had between the parts.

claim-z vA dial. indicator comprising a casing, a rack 20,;movable inand. out of said casing, a unit containing.. operatingy mechanism and apinion to mesh with said rack, said unit comprising a pairof' platesvone of which ts the inner surfaces-.of said casing to locate the unittherein and is movable With reference to the casing to cause .engagementof saidpinion with said rack until the. desiredfm'esh. ot raokand'pinionis obtained. l

JOHN H. WORTI-IEN.

REFERENCEsV CITED The;- following references Vare; ofy `record in 'thel'e of. this patent; Y l

' UNITED STATES PATENTS lliluxn'ber A Name. Date l 517.54m TrowbridgeJan. 19,1897 894.314 Cashmere July 28, 1908 1.119.256 gaten. Dee.1,*1914 4,439,738 v Howland -oct 3,`r 1922 1,637,024. 'Maynard July-26,i927 y12,093,308', cook sept. 1.1171933-

